在Java中，可以使用以下方法將文件從網絡下載到本地：

1. 使用Java標準庫中的URL類和URLConnection類：

import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
public class FileDownloader {
public static void main(String[] args) {
String fileUrl = "http://example.com/file.txt";
String savePath = "C:/path/to/save/file.txt";
try {
URL url = new URL(fileUrl);
URLConnection connection = url.openConnection();
// 獲取文件大小
int fileSize = connection.getContentLength();
// 創建輸入流
InputStream inputStream = new BufferedInputStream(url.openStream());
// 創建輸出流
FileOutputStream outputStream = new FileOutputStream(savePath);
byte[] buffer = new byte[1024];
int bytesRead;
int downloadedSize = 0;
// 逐個字節讀取并寫入文件
while ((bytesRead = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
downloadedSize += bytesRead;
System.out.println("下載進度：" + (downloadedSize * 100 / fileSize) + "%");
}
// 關閉流
outputStream.close();
inputStream.close();
System.out.println("文件下載完成！");
} catch (IOException e) {
e.printStackTrace();
}
}
}

2. 使用第三方庫Apache HttpClient：

import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import java.io.FileOutputStream;
import java.io.IOException;
public class FileDownloader {
public static void main(String[] args) {
String fileUrl = "http://example.com/file.txt";
String savePath = "C:/path/to/save/file.txt";
try {
CloseableHttpClient httpClient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet(fileUrl);
// 發送請求并獲取響應
CloseableHttpResponse response = httpClient.execute(httpGet);
// 讀取響應內容
byte[] fileData = EntityUtils.toByteArray(response.getEntity());
// 將文件內容寫入本地文件
FileOutputStream outputStream = new FileOutputStream(savePath);
outputStream.write(fileData);
// 關閉流
outputStream.close();
response.close();
httpClient.close();
System.out.println("文件下載完成！");
} catch (IOException e) {
e.printStackTrace();
}
}
}

無論使用哪種方法，都需要提供文件的URL和要保存到的本地路徑。這些示例中使用的是文本文件，但同樣適用于其他類型的文件。